On Tue, Jan 25, 2011 at 10:03 AM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Heikki Linnakangas <heikki.linnakangas@enterprisedb.com> writes:
>> Detoasting on first usage, ie. exec_eval_datum(), seems the best to me.
>> Compared to detoasting on assignment, it avoids the performance
>> regression if the value is never used, and I don't think checking if the
>> value is toasted at every exec_eval_datum() call adds too much overhead.
>
> The arguments that were made against this were about maintenance costs
> and code footprint. Claims about performance are not really relevant,
> especially when they're entirely unsupported by evidence.
How much evidence do you need to the effect that detoasting a value
that's never used will hurt performance?
--
Robert Haas
EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company
